Wireless LAN technology has become the actual standard for wireless Internet access, with increasing availability of access points for those wireless networks as a result of what they offer of high data rates, low roaming costs, and good in-building coverage. This led to a strong trend to the inclusion of Wi-Fi embedded sub-system in all kinds of devices included computing side, and embedded side.The smartphones with the adoption of Wi-Fi technology had to meet two requirements: 1- quality of service support for prioritizing real-time applications. 2- inclusion of power saving functionality to achieve an operating time meets the expectations of users. This paper presents a new power management technique P-PSM, it is a combination of medium access mechanism depends on Contention Window to provide the quality of service, with standard power management technology stdPSM. In addition to evaluate its performance against a set of power management techniques under changing the number of network nodes in order to clarify the expected quantity differences in terms of both quality of service and power saving.